DNA binding and bending are necessary but not sufficient for Fis-dependent activation of rrnB P1.

AUTOR(ES)

Gosink, K K

RESUMO

The Escherichia coli Fis protein binds to three sites in the upstream activation region of the rrnB P1 promoter and enhances transcription 5- to 10-fold in vivo. In this report, we investigate the mechanism of Fis-dependent activation of transcription. We show that stimulation of rrnB P1 transcription by Fis can occur on linear DNA templates and does not require DNA upstream of the promoter-proximal Fis site I. Mutants of Fis defective for Hin-mediated recombination have been isolated previously and have defined an N-terminal domain required for DNA inversion by Hin in addition to the C-terminal domain which is required for DNA binding. Several of these mutants were found to be defective in stimulation of rrnB P1 transcription in vivo and in vitro. Activation-defective mutants fall into three classes: those that fail to bind to the upstream activation region, those that bind but fail to bend the DNA normally, and those that bind and bend but still fail to activate transcription. We conclude that it is unlikely that Fis functions by simply bringing upstream sequences or bound factors into the proximity of RNA polymerase to activate transcription. Rather, the data are most easily interpreted in terms of transcription activation by direct interactions between Fis and RNA polymerase, requiring precise positioning of the two proteins facilitated by bending of the DNA binding site.

Documentos Relacionados

• Both fis-dependent and factor-independent upstream activation of the rrnB P1 promoter are face of the helix dependent.
• FIS-dependent trans activation of stable RNA operons of Escherichia coli under various growth conditions.
• Growth rate-dependent control of the rrnB P1 core promoter in Escherichia coli.
• Localization of the intrinsically bent DNA region upstream of the E.coli rrnB P1 promoter.
• Regulation of the Escherichia coli rrnB P2 Promoter